Latest ArticlesWe propose a concept for ligase detection by conversion of aggregation-based homogeneous analysis into surface-tethered electrochemical assay through streptavidin (SA)-biotin interaction. Sortase A (SrtA) served as the model analyte and two biotinylated peptides (bio-LPETGG and GGGK-bio) were used as the substrates. SrtA-catalyzed ligation of the peptide substrates led to the generation of bio-LPETGGGK-bio. The ligation product (bio-LPETGGGK-bio) induced the aggregation and color change of SA-modified gold nanoparticles (AuNPs) through the SA-biotin interactions, which could be assayed by the colorimetric method. Furthermore, we found that the bio-LPETGGGK-bio could trigger the assembly of tetrameric SA proteins with the formation of the (SA-bio-LPETGGGK-bio)n assemblies through the same interactions. The above results were further confirmed by atomic force microscopy and fluorescent imaging. The insulated assemblies were in-situ fabricated at the SA-modified gold electrode, thus hindering the electron transfer of [Fe(CN)6]3−/4− and leading to an increase in the electron-transfer resistance. The capability of the method for the detection of SrtA both in vitro and Staphylococcus aureus (S. aureus) has been demonstrated. SrtA with a concentration down to 1 pmol/L has been determined by the electrochemical analysis, which is lower than that achieved by the colorimetric assay (50 pmol/L). By integrating the advantages of homogeneous reaction and heterogeneous detection, the strategy serves as an ideal means for the fabrication of various sensing platforms by adopting biotin-labeled and sequence-specific peptide or nucleic acid substrates.
Rapid screening of foodborne pathogens is of great significance to ensure food safety. A microfluidic biosensor based on immunomagnetic separation, enzyme catalysis and electrochemical impedance analysis was developed for rapid and sensitive detection of S. typhimurium. First, the bacterial sample, the magnetic nanoparticles (MNPs) modified with capture antibodies, and the enzymatic probes modified with detection antibodies and glucose oxidase (GOx) were simultaneously injected into the microfluidic chip, followed by mixing and incubation to form MNP-bacteria-probe sandwich complexes. Then, glucose with high impedance was injected into the chip and catalyzed by the GOx on the complexes into hydrogen peroxide with high impedance and gluconic acid with low impedance, which was finally measured using the low-cost interdigitated microelectrode and the electrochemical impedance analyzer to determine the target bacteria. Under the optimal conditions, this biosensor could quantitatively detect S. typhimurium at the concentrations from 1.6 × 102 CFU/mL to 1.6 × 106 CFU/mL in 1 h with the low detection limit of 73 CFU/mL. Besides, this biosensor was demonstrated with good feasibility for practical applications by detecting the S. typhimurium spiked chicken meat samples.
The efficient remediation of heavy metal complexes in water has become a difficult and challenging task owing to their high stability and strong mobility. In this study, a novel strategy was employed for highly efficient removal of Cu-citrate by using intimately coupled photocatalysis and biodegradation (ICPB) system with non-woven cotton fabric as a carrier. Experimental results showed that the ICPB system caused 94% Cu removal, which was higher than those of single photocatalysis. After 5 cycles, Cu removal efficiency could still reach 78% within 5 h. The existence of 0–40 mg/L citrate had negligible influence, whereas the presence of 60–100 mg/L citrate exhibited a limited adverse effect on Cu removal (~70%). The decomplexation of Cu-citrate was realized via the function of free radicals and microorganisms. Two main processes, such as bio-adsorption of Cu2+ by microorganisms, deposition of Cu0 on the surface of material, played important role in Cu removal from aqueous solution. The dominant microorganisms in the system were Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Chlorophyta, Planctomycetes, and Verrucomicrobia. Furthermore, the performance of ICPB system was also validated through treatment of other heavy metal complexes. This study provided a feasible strategy for the decontamination of heavy metal complexes in wastewater.
Osteonecrosis of the femoral head (ONFH) is a devastating musculoskeletal disease characterized by the impaired circulation of bone. The purpose of this study was to explore the underlying mechanisms of the protective effect of icariin on the glucocorticoid-induced injury of bone microvascular endothelial cells (BMECs). Normal BMECs were extracted from the femoral heads by enzymatic isolation and magnetic-activated cell sorting methods. Dexamethasone and icariin were used to intervene BMECs in microfluidic organ chips, and phalloidin staining was conducted to observe the cell morphology and viability. Then next-generation transcriptome sequencing and real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were performed to identify the differentially expressed genes (DEGs) in different groups. Through the microfluidic organ chip, it can be observed that after dexamethasone intervention, the filamentous structure in cell fibers disappeared and the cell morphology changed from spindle to round until death. Icariin could relieve these changes and showed a protective effect on glucocorticoid-damaged BMECs. In addition, 201 DEGs were detected between the icariin protection group and the dexamethasone group, which were significantly enriched in 17 signaling pathways. 8 of the top ten selected hub genes (IL6, PTGS2, VEGFA, etc.) were confirmed by qRT-PCR. Transcription factors (TFs)-gene network showed 63 connections between 18 TFs and 12 DEGs. For instance, GATA2 could regulate 5 DEGs. The associations between 92 miRNA and 12 DEGs were visualized in a miRNA-gene network. The hub miRNA, has-mir-335–5p was predicted to interact with 8 DEGs (PTGS2, VEGFA, etc.). Microfluidic organ chips could provide excellent morphological results for cell experiments, by which it could be observed that icariin showed a protective effect on the glucocorticoid-induced injury of BMECs. Beside, these DEGs, possible regulatory TF (GATA2, FOXC1, etc.) and miRNA (has-mir-335–5p) might be dysregulated in the initiation of ONFH and have prospective importance in ONFH diagnosis and therapy.
The asymmetric carbenoid CH insertion of 3-diazooxindoles into 1, 4-cyclohexadiene has been accomplished in the presence of chiral bis(imidazoline) NCN pincer iridium(Ⅲ) complexes as the catalysts. With a catalyst loading of 0.5 mol%, the reactions proceeded smoothly at 0 ℃ to afford a variety of chiral 3-substituted oxindoles in good yields with moderate to excellent enantioselectivities (up to 99% ee). The protocol exhibits good functional group tolerance with respect to 3-diazooxindoles and is readily scaled up to 2 mmol scale without any loss in activity and enantioselectivity. Density functional theory (DFT) calculations have been performed to better understand the reaction mechanism and to explain the stereochemical outcome of the reactions.
In this study, SB216763 and cyclosporine A were identified as anti-influenza A virus (IAV) agents by transcriptome signature reversion (TSR) analysis through deep mining of the cellular transcriptome of human airway and lung cell lines infected with 3 strains of IAV and the chemical perturbations library. A synergistic effect of SB216763 and cyclosporine A against influenza A was disclosed by quantification of the network-based relationship, which was validated in vitro. Along with burgeoning omics approaches, transcriptome-based drug development is flourishing, which provides a novel insight into antivirals discovery with comprehensive cellular transcriptional information of disease and chemical perturbations in multicomponent intervention. This strategy can be applied as a new approach in discovering multitarget antiviral agents from approved drugs, clinical compounds, natural products or other known bioactive compounds.
The small molecular second near-infrared (NIR-Ⅱ, 1000-1700 nm) dye-based nanotheranostics can concurrently combine deep-tissue photodiagnosis with in situ phototherapy, which occupies a vital position in the early detection and precise treatment of tumors. However, the development of small molecular NIR-Ⅱ dyes is still challenging due to the limited electron acceptors and cumbersome synthetic routes. Herein, we report a novel molecular electron acceptor, boron difluoride formazanate (BDF). Based on BDF, a new small molecular NIR-Ⅱ dye BDF1005 is designed and synthesized with strong NIR-Ⅰ absorption at 768 nm and bright NIR-Ⅱ peak emission at 1034 nm. In vitro and in vivo experiments demonstrate that BDF1005-based nanotheranostics can be applied for NIR-Ⅱ fluorescence imaging-guided photothermal therapy of 4T1 tumor-bearing mice. Under 808 nm laser irradiation, tumor growth can be effectively inhibited. This work opens up a new road for the exploitation of NIR-Ⅱ small molecular dyes for cancer phototheranostics.
Aqueous rechargeable Ni−Zn batteries are considered as a new generation of safe and reliable electrochemical energy storage system. However, low electronic conductivity of Ni-based cathodes hinders the practical application of Ni-Zn batteries. This problem can be overcome by compositing the Ni-based cathode with highly conductive carbon substrates. A chemical oxidation pre-treatment is popularly applied to the carbon substrates to increase their hydrophilicity and thus facilitate the growth of active materials in aqueous systems. However, the anodic stability of the oxidized carbon substrates is greatly challenged, which has never been addressed in previous reports. In this work, we first compared the anodic stability of carbon fiber paper with and without oxidation treatment and find that carbon substrate with the chemical treatment caused remarkable oxidization current in the required voltage range. To take both anodic stability and fine growth of active materials into account, here we demonstrated a facile physical surface-treatment method of ethanol wetting to replace the chemical treatment. The ethanol infiltration removes gas adsorption on carbon substrates and thus promotes their hydrophilicity. This cost-effective strategy simultaneously achieves a high anodic stability and a fine growth and uniform distribution of nickel-cobalt hydroxide on the carbon microfibers. The resulting Ni-Zn battery provides a high discharge capacity of 219 mAh/g with an operation cell voltage of 1.75 V.
The first intermolecular electrophilic dearomatization of halonaphthols with benzyl/allyl bromides is described. Halonaphthols are used as carbon-nucleophiles in dearomatization to form three-dimensional cyclic enones with excellent chemoselectivity, in which etherification of phenolic hydroxyl group could be restrained well by using cesium carbonate as the base. A wide range of cyclic enones is directly prepared from various substituted benzyl/allyl bromides and halonaphthols. Mechanistic investigations suggest a direct SN2 reaction pathway.
Molybdenum trioxide (MoO3) can be employed as an excellent host for intercalation due to its 2D layered structure that connected by van der Waals interactions. Herein, a series of polyoxometalate-based MoO3 composites (Al13@MoO3) were successfully prepared by interpolating the Keggin-type polycationic AlO4Al12(OH)24(H2O)127+ (Al13) into MoO3 gallery. These composites can be applied to rapidly adsorb the anionic dye methyl orange (MO) through strong electrostatic interactions lead to compact and stable gathering in the surrounding of the numerous charged Al13. Adsorption behaviors of composites with the different amount of Al13 were determined, these results revealed that Al13-3.34%@MoO3 exhibited the most remarkable adsorption capacity. More importantly, the composite maintains superior adsorption capacity for five consecutive adsorption/desorption cycles, suggesting that Al13@MoO3 can be an efficient and durable adsorbent.
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